Why would anyone suspect this may be due to transport damage of the gearbox? Maybe if you had any idea of what the damage may have been, then maybe, just maybe you could speculate.
But without knowing what happened, then you have no grounds to speculate. This could be something as simple as damaged threads of the generator/alternator studs. It could also have been bounced off the back of the transport trailer going down the highway ... Tumbling down the highway, smashing through a couple construction barriers and eventually coming to rest at the bottom of a lake. Either way, it was sent back to AH (despite the rumours on here of heli-one) and I'm sure was inspected/repaired accordingly.